Micromechanical modelling of typical Dense Bitumen Macadam (DBM) from laboratory testing and X-ray Computed Tomography (CT)

The application of finite element modelling for assumed mesh elements is limited for asphalt mixtures because of the inclusion of air voids within the structure. A multiphase finite element (FE) model was applied to consider the effect of air voids on the properties of asphalt mixtures. The virtual microstructure of an asphalt mixture was incorporated into the FE model from the X-ray CT images of asphalt specimens. Considering the asphalt mixture as viscoelastic, the mechanical properties determined from laboratory tests were applied to the FE model. Analysis was performed on a representative volume element using the concept of continuum damage mechanics. It was found that X-ray CT images can be converted into a finite element mesh of the real geometry of the asphalt sample. It was also found from the analysis that the mesh generated from the actual geometry account of the stress concentrations due to air void distribution compared with the assumed simplified geometry. The FE model was also analysed using CAPA 3D to give a validation of the results.